Method of containing radiation using fullerene molecules

ABSTRACT

This specification presents methods of containing/absorbing alpha, beta, gamma, X-ray, and neutron radiation using Fullerene molecules employing the resonant relativistic absorption phenomena based on a frequency dependant Doppler effect. Radioactive atoms, ions, and molecules (X rad ) are encapsulated in a variety of Fullerene molecules (C 60 , onions, nanotubes, and capsules). The resulting radioactive material-holding Fullerene complexes (X rad  @C n ) will either decrease the intensity of escaping internally-generated radioactive emissions or, in certain optimal cases, absorb and/or contain all such internally-generated radioactive emissions which occur as the radioactive material decays.

1. Field of the Invention

The placement of radioactive matter inside Fullerene cages is detailedin the present invention. This radioactive matter, including nuclearwaste or specifically chosen radioactive material, and the radiationemitted by such matter is completely contained with the cages (radiationcontainment depends primarily on the cage structure chosen andconditions of storage), thus providing an attractive long-term disposaloption. Predetermined release of the emitting radiation is alsodiscussed. The present invention relates to means and products thatsecurely store radioactive materials while minimizing harmfulradioactive emissions to the surrounding environment.

2. Background of the Invention

The secure long-term disposal of radioactive nuclear waste has become acritical issue throughout the world. Virtually every advanced countryhas developed its own, often times elaborate, approach to long-termstorage and safe disposal of radioactive wastes. Currently, the UnitedStates plans to store radioactive wastes inside glass, ceramic,concrete, or clay containment vessels. These vessels are designed tocontain the dangerous radioactive materials for hundreds of years.

Given the dangers associated with radioactive emissions from nuclearwastes, merely containing these wastes within containment vessels is notenough. Indeed, given the known dangers of radiation posted by storingradioactive wastes, the U.S., in an effort to minimize radiationdangers, plans to bury these radioactive containment vessels deep withinthe earth in geologically secure environments (e.g., natural salt bedformations). However, these extravagant storage sites are extremelyexpensive to develop, operate, and maintain. Moreover, there are realethical considerations involved in planning for the safe storage ofwaste products with hazardous half-lives several times longer than thelongest known enduring human civilization. For example, the gammaradiation half life of ²³⁸ U is 4.51×10⁹ years, and ²⁴⁴ Pu has a betaradiation half life of 7.6×10⁷ years. The issue that must be addressedis how to ensure the safety of the present and future generations fromhigh energy ionizing radiation produced by nuclear waste. This is anissue of concern not only for the scientific community, but for thegeneral public as well. In fact, the problem of proper and safe nuclearwaste disposal is perceived as having no viable solution. Simply put,people are afraid of plans to store radioactive wastes anywhere nearthem, and the selection of an appropriate storage site has triggeredseveral intense legal and political debates.

In an effort to address the problems of storing nuclear wastes, anothergroup of researchers patented the structural benefits of Fullerenemolecules and their advantageous use for storing waste materials basedon the structural and chemical properties of the entire class ofFullerenes. This approach is disclosed in U.S. Pat. No. 5,350,569,issued to Nicholas V. Coppa, September, 1994 (referred to as the Coppapatent). Recognizing the inherent structural strengths of Fullerenemolecules, the Coppa patent teaches storing nuclear wastes insideFullerene molecules. In particular, the Coppa patent refers to thestructural and chemical properties that make Fullerenes suitable as astorage mechanism and criticizes the known radioactive waste storagemethod (e.g., metal ions in a glass matrix) as being prone to structuraldamage such as that damage caused by radioactive decay.

A second, related research effort aimed at radioactive waste storageutilizes very large Fullerene cages (Giant Onions or Nanotubes) toencapsulate radioactive material. The large molecular soots created inthis approach typically measure hundreds of nanometers across and do notrotate. The results of this research were recently patented in Argentina(Act No: 0333793, date of issue Oct. 10, 1995) by Dr. Enrique Pasqualiniet al. (referred to as the Pasqualini patent). Significantly, both theCoppa and Pasqualini patents fail to teach 1) how to use certainspecific Fullerene cages to contain internally-generated radioactiveemissions, 2) which Fullerene cages will contain or decrease suchradioactive emissions, or 3) the external physical conditions necessaryfor sustaining the radiation containing/absorbing properties of theX_(rad) @C₆₀ Fullerenes. Indeed, complete protection from radiation viaclassical absorption (as in these two related patents) into statichexagonal carbon lattices would require material cross sections measuredin meters.

In a more distantly related use of Fullerene cages, Australian scientistBill Bruch of the National University in Canberra uses Fullerene carboncages as a medical imaging agent introduced into live tissue. The giantFullerenes used by Bruch have 540 or more carbon atoms with theradioactive material, technetium (Tc), inserted into the large hollowinterior of the cages. The technique is called "Technegas," a namederived from the method used to obtain images of the interior of thelungs. Prior to imaging, the subject inhales a gas laced with Tc@C₅₄₀₊,which lodges in the lungs. The radiation of the technetium is detectedusing a camera sensitive to gamma rays, thereby producing an image ofthe interior of the lungs. Today, there are about 150 Technegas systemsin use in 18 countries around the world including the UK, Germany,France, Italy, and Japan. However, like the Coppa and Pasqualinipatents, the "Technegas" approach fails to teach the use of Fullerenecages to contain internally-generated radioactive emissions.

3. Relevant Fullerene Background Information

In September 1990, for the first time since the discovery of Fullerenesin 1985, the Huffman/Kratschmer research team developed a method toproduce macroscopic amounts of solid C₆₀ via electric arcs (PatentApplication Number #PCT/US91/05983, Filing Date Aug. 21, 1991). Thisdevelopment stimulated a large amount of new research on Fullerenes andtheir possible uses in the scientific and technological community.Several Fullerene production methods now exist.

3.1 Basic Relevant Fullerene Properties

The geometrical structure of Fullerene molecules must have exactly 12pentagonal faces, but may have any number (except 1) of hexagonal faces.Exact icosahedral symmetry (called Ih symmetry) is possessed by aspecial subset of the Fullerenes. The first four Fullerenes with Ihsymmetry are: C₂₀, C₆₀, C₈₀, and C₁₄₀. C₆₀, the quintessentialFullerene, is named Buckminsterfullerene. Fullerenes are described bythe general formula C₂₀ +2H, where H is the number of hexagonal faces.

For C₆₀, both theoretical calculations and Scanning Tunneling Microscopy(STM) experiments have shown that electron currents exist in themolecule's pentagons and hexagons. Calculated ring current chemicalshifts, based on London theory, show the existence of remarkable "pi"electron ring currents in the pentagons. STM experiments demonstrateboth a high level surface energy concentration in the pentagons and theclosed-shell electronic structure of C₆₀. Thus, C₆₀ is unique among theFullerenes, possessing an electronically closed shell with a very highconcentration of energy in the pentagons.

Electronic closure for a Fullerene molecule means that the electroncloud surrounding the molecule is continuous. In single layer Fullerenesother than C₆₀, the hexagons are regions which are not electronicallyclosed. For C₆₀, the combination of perfect Icosahedral Symmetry and anelectronically closed shell gives the C₆₀ molecule the properties of a"big atom."

3.2 Fullerenes Can Encapsulate Other materials

Shortly after the Huffman and Kratschmer discovery, researchers,including the present inventor, found that the electronically closedshell structure of the C₆₀ Fullerene molecule results in an includedspace completely void of all matter, providing an absolutely purevacuum. Later, using different methods of fabrication, it was discoveredthat metal ions could be inserted into the Fullerene's internal hollowcenters, a process commonly referred to as "doping" the Fullerene.Multiple methods of producing "doped" Fullerenes are possible, therebycreating another entire new series of materials. Because the volume ofan empty C₆₀ molecule is larger than any atom in the periodic system ofelements, all possibilities for forming M@C₆₀ complexes should exist.(Note: the @ symbol indicates that the metal atom, M, is inside the C₆₀cage.)

For example, macroscopic quantities of Fullerenes containing a metalatom were first produced using lanthanum atoms. This was accomplished bylaser vaporization of a La₂ O₃ on graphite composite rod in a 1200° C.tube furnace. Other methods of forming doped M@C₆₀ Fullerenes includeusing a laser vaporization/high temperature furnace technique in which aCaO/graphite rod is fabricated by mixing graphite powder and graphiticcement resulting in the formation of Ca@C₆₀ complexes. Efficientproduction methods for doping Fullerenes are still in development.

3.3 Fullerene Tubes, Capsules, and onions

Fullerene capsules and nanotubes are cylindrical carbon molecules withstructurally closed cages. Capsules have hemispherically closed ends,with each end having six pentagons (the same as 1/2 of aBuckminsterfullerene). Nanotubes are closed on one end with a sixpentagon hemisphere, but remain open on the other end. Fullerenecapsules range from 2 nm to 100 nm in length. Nanotubes range from 1 nmto 100 nm in diameter and from 0.1 microns to 10 microns in length.Capsules and nanotubes can be formed as concentric multi-layer orsingle-layer shells. Because of their shorter lengths, capsules may benested as inner layers within either larger capsules or nanotubes.

Fullerene onions are multi-layered spherical carbon cage structures withexactly 12 pentagons in each layer. The pentagons are located on theicosahedral axes and the number of hexagons varies. Between any twolayers (shells), the effects of van der Waals attractions work out anoptimized relative position and spacing.

4. Radiation Background Information

Nuclear materials give off five (5) main types of radiation: 1) alpharadiation (a helium nucleus with a velocity of about 10⁹ cm/s), 2) betaradiation (a high velocity negative electron, the velocity of some betaparticles is as great as 0.996 that of the speed of light), 3) gammaradiation (electromagnetic radiation of a very short wavelength and highenergy that is released when a neutron strikes a proton), 4) X-rays(radiation of an extremely short wavelength, very high energy, and oftenassociated with electromagnetic waves), and 5) neutron radiation emittedby certain radioactive materials (similarly high energy but lesscommon). These five types of ionizing radiation are referred to here as"harmful radiation." Even after radioactive material has been securelystored within large containment vessels, the existence of these harmfulemissions requires that additional measures be taken to protect againsta future release of harmful radiation.

5. Objects of the Present Invention

Although the Coppa patent discloses "doping" Fullerenes with metal ionsas a way of storing radioactive materials, the processes described willnot remove the dangers posed by the radiation emitted from thesewaste-in-Fullerene complexes. Indeed, in order to safely andconsistently eliminate the harmful high energy radiation, it isnecessary to consider the radiation emitted from the specific wastestored, the exact Fullerene molecule used, and the conditions underwhich the molecule is maintained. This is accomplished by identifyingthe specific useful properties of different classes of Fullerenes andapplying them toward desired outcomes.

Thus, one object of the present invention is to provide a means forstoring radioactive wastes or other radioactive materials whilecontaining, absorbing, trapping, or suppressing the harmful radioactiveemissions generated by the decay of the stored material. The containmentof these radioactive emissions minimizes the radiation dangers andobviates the need to create the elaborate underground storage sitescurrently contemplated.

It is another object of the present invention to provide a means tostore radioactive wastes or other radioactive materials while reducingand/or redirecting the external emission of the harmful radiationreleased from the nuclear storage molecule.

Other objectives and additional beneficial features of the invention areset forth in the following description.

SUMMARY OF THE INVENTION

The invention provides a method for containing/absorbing all types ofhigh energy ionizing radiation using Fullerene molecules. Under certainconditions, the harmful radiation emitted from atoms, ions, and/ormolecules of radioactive materials encapsulated within Fullerenemolecules may be decreased or eliminated. A storage molecule describedherein will prevent the release of harmful radiation far into thefuture.

DETAILED DESCRIPTION

The present invention provides a means and mechanism by whichradioactive materials may be permanently isolated from their externalenvironment while simultaneously reducing or eliminating the hazardspresented by radioactive emissions from these materials. Central to theinvention is the precise knowledgeable utilization ofBuckminsterfullerenes and Fullerenes.

There are three main types of Fullerene molecules that can besuccessfully employed to reduce or eliminate emitted radiation. OneFullerene molecule in particular, the sixty carbon atomBuckminsterfullerene molecule (designated C₆₀), is used as the primarystorage molecule in order to contain all of the harmful, high energyionizing nuclear radiation emitted from the stored radioactive material.In addition, Fullerene onions, and Fullerene nanotubes and capsules canalso be used to reduce the harmful, high energy ionizing radiation.

1.0 Buckminsterfullerene, C₆₀, the Perfect Fullerene Completely ContainsRadiation

C₆₀ is the only single-layer Fullerene molecule that will completelycontain high energy ionizing radiation. Under specific temperature andpressure conditions, C₆₀ can completely absorb the five main types ofharmful, high energy, ionizing radiation; namely, alpha, beta, gamma,X-ray, and neutron radiation. Although the ability to partially absorbharmful radiation from encapsulated radioactive material is shared by avariety of Fullerenes, only the C₆₀ molecule can contain (contain orabsorb) the harmful external radiation via frequency dependentDoppler-based effects. For radiation originating inside of a quicklyspinning C₆₀ molecule, the classical superposition of radiation does notexist. It is replaced by the relativistic superposition of radiation.This containing/absorbing mechanism is referred to herein as "resonantrelativistic absorption."

To grasp how this method of containing/absorbing radioactive emissionsworks, it is necessary to thoroughly understand three key points aboutFullerenes. These three key points are:

1) C₆₀ has a unique 3-dimensional spherical structure that possesses anelectronically closed shell,

2) C₆₀ possesses a perfect vacuum inside its molecular cage large enoughto hold up to 2 atoms (or, oftentimes, many ions) of any element fromthe periodic table including large radioactive elements such as uraniumor plutonium, and

3) C₆₀ rotates, with same probability in all directions, at very highspeeds (between ten and thirty billion times per second), in vacuum, gasphase, liquids, and solid state.

If maintained under appropriate conditions, then because of these threekey points, C₆₀ exhibits what is termed here "resonant relativisticabsorption phenomena" to effectively contain all harmful radiation.

1.1 C₆₀ Contains a Wide Range of Harmful Radiation

The ability of C₆₀ to effectively absorb or contain internally emittedradiation is described herein for all five harmful radiation types:alpha, beta, gamma, x-rays, and Neutrons.

The alpha radiation emitted by an encapsulated radioactive material willbe contained within the C₆₀ storage molecule. An alpha particle isequivalent to a helium nucleus, a two proton and two neutron complex.Classically, alpha radiation is the easiest radiation to absorb. WithC₆₀ as the storage molecule, the absorption of alpha radiation can beaccomplished in a relativistic way based on the Doppler effect.

Based on a preliminary calculation of the electron affinity of theUranium-C₆₀ complex, the interactions between the Uranium and the insideof the C₆₀ will be strongly covalent, because the binding energy is 1.87eV lower than in the normal covalent state of UO₂. This means that theUranium will be in a fixed position on the inside surface of the C₆₀cage. Furthermore, two 7s electrons and one 6d electron will go to theT_(1u) molecular orbital of C₆₀, increasing the electronic density ofthe cage. This is a clear indication that the ground state of U@C₆₀complex is ³ T_(1u). However, due to the presence of the uranium atominside the cage, there will exist an alpha particle that will take twoelectrons from the H_(u) molecular orbital of C₆₀.

Because Fullerene C₆₀ rotates very fast under the appropriate conditions(3×10¹⁰ s⁻¹ in solid state), and because the alpha particles move inradial direction (at about 10⁹ cm/s), the two moments act together as anorthonormal one and will have coupling constant bonds in a space-timesystem with a single point. These coupling phenomena lead to a "softtouch" between the electronic surface of the cage interior (de-localized"pi" electrons) and the alpha particle.

A significant contribution to the formation of the "soft touch" comesfrom the polarization energy generated by the high spin rates of thecages. The alpha particle is weakly neutralized (a "false helium") andmoves around on the inside cage surface. Based on the initial energy ofthe alpha particle (about 4 MeV), the Fullerene rotation, and the weakinteraction with the de-localized electronic cloud, the "false helium"will stay trapped moving inside the C₆₀ cage. The radioactive alphaemission from the encapsulated radioactive material will be forevercontained within the Fullerene molecule.

The quickly spinning C₆₀ Fullerene will also contain the beta radiationemitted from the encapsulated materials. Beta radiation originates as anelectron released from the nucleus when a neutron is converted into aproton. Beta particles, being fast-moving electrons, contain energy ofup to about 1.6×10⁻¹³ J. Because beta particles have a much smaller massthan other charged particles, they attain velocities that are anappreciable fraction of the speed of light (0.97 to 0.999 % of the speedof light).

There is an important difference between classical absorption, whichemploys a fixed absorber, and relativistic absorption (based on theDoppler effect), in which case the absorber is rotating at speedsapproaching the speed of the radiation (light). In this lattersituation, there will exist both time resonant phenomena and thetransfer of energy from a very fast electron (beta radiation) to C₆₀ andfrom C₆₀ to a delocalized energy shell around the C₆₀. This is the"resonant relativistic absorption" referred to above.

In the case of beta radiation, the relativistic phenomena first leads tothe absorption of the beta radiation (increased rotation) and then to are-distribution in a delocalized electron shell. The maximum energy thatcan be absorbed via conventional absorption (Ea) by C₆₀ in itsunoccupied orbitals is only about 320 eV (sixty electrons in eightmolecular orbitals T_(2g), G_(u), G_(g), H_(u), T_(2u), H_(g), T_(1g),and T_(1u) with 48, 60, 52, 55, 30, 48, 15, and 12 eV, respectively).This classically absorbed energy will increase both the ring current inthe pentagons and hexagons, and will increase the volume of the C₆₀. Therise in ring currents will also slightly increase the rotation speed ofthe C₆₀ molecule. However, the total amount of beta radiation energyabsorbed in this manner is minimal. Thus, the majority of beta radiationenergy must be absorbed by the C₆₀ molecule via resonant relativisticabsorption.

As referenced before, the ability of C₆₀ to use relativistic absorptionto absorb harmful radiation essentially depends on the storagemolecule's rotation rate. Experimental evidence indicates that C₆₀rotates at 1.8×10¹⁰ s⁻¹ in solution (Tolvene and at 3.0×10¹⁰ s⁻¹ insolid state. The energetic sources of this rotation are the ringcurrents in the 12 pentagons and 20 hexagons.

The relativistic resonant aspects of containing beta radiation withinC₆₀ necessitate consideration of the energy relation through the law ofenergy conservation (E_(initial) =E_(final)). The radiation energy (Er)inside the C₆₀, the absorption energy of the C₆₀ (Ea), and the externalenergy in a delocalized electronic cloud of the C₆₀ (Eh) are related toone another by the energy conservation law as Er=Ea+(K×Eh), where:##EQU1## In the above expression, v_(r) is speed of radiation(space-time phenomena), and ω is C₆₀ rotation (time phenomena).

For the resonant relativistic absorption phenomena, the main feature isK, which depends on the dielectric permittivity k. Because the inside ofC₆₀ is a perfect vacuum, the permittivity (e₀) is 8.854×10⁻¹² C² N⁻¹ m².Keeping in mind that the radiation energy (Er) and the externaldelocalized electron cloud (Eh) have similar values, then the dielectricpermittivity (Er/Eh) of the C₆₀ electronic shell is approximately equalto 1, or slightly less than 1, with the difference ranging from a1×10⁻¹⁰ to 10⁻²⁰ value.

The general equation for the relativistic relationship betweenfrequencies measured in two reference frames is given by therelativistic Doppler equation: ##EQU2##

The relationship between frequencies measured in two reference framesthat are moving perpendicularly, such as is the case in U@C₆₀ complexes(α=π/2, cosα=0), is: ##EQU3##

When one reference frame (C₆₀) rotates very fast (3×10¹⁰ s⁻¹) around asource of radiation, while another reference frame (radiation) travelsclose (slighly less than) to the speed of light (3×10¹⁰ cm/s), aphenomena, referred to here as a resonant relativistic absorption,occurs in the space of 1 cm from the source of radiation. This phenomenais expressed as: ##EQU4##

Accordingly, the key points regarding the relativistic absorption ofbeta radiation (frequency of about 10²⁰ s⁻¹) are the C₆₀ rotation rate(remarkably high) and the delocalized electronic cloud (very large atapproximately 1 cm radius, with a frequency approximately 1.41×10¹⁰ s⁻¹)of the X_(rad) @C₆₀ complex. These properties are central to permittingthe use of C₆₀ as a storage molecule which can protect the externalenvironment from the internally-generated harmful beta radiation.

Turning to gamma radiation, from the nuclear waste radiationperspective, gamma rays can be conceived of as particles of light or asbundles of energy (photons). The gamma ray can be imagined to be eithera burst of energy (a particle) or a wave that represents part of thebinding energy difference between the nucleus that disintegrates and thesubsequent nucleus that is formed.

There are three additional main types of gamma radiation generated byother particle interactions. These three secondary forms of gammaradiation are produced by: 1) the Compton scattering effect, 2) thephotoelectric effect, and 3) the electron-positron pair production. Ofthe three types of Gamma radiation produced by such particleinteractions, only the photoelectric effect is possible within aFullerene.

The photoelectric effect is produced when a gamma photon hits an orbitalelectron of an atom and transfers its energy to the electron, which thenshoots out into an outer shell. As the affected electron springs back toits original position, energy is re-radiated as gamma radiation of alonger wavelength than the original gamma radiation.

The longer wavelength gamma photons created by this effect will havemuch less penetrating power than the original gamma rays that createdthem and, therefore, are classically easier to absorb. In the case ofnuclear materials encapsulated in Fullerenes, both the high energy gammaray (from the interior nuclear material) and the lower energy gamma ray(produced by photoelectric effect) are trapped by the spinning,electronically closed-shell molecules.

The containment of all types of gamma radiation within C₆₀ is approachedin much the same way as alpha and beta radiation containment.Specifically, the resonant relativistic absorption principal is employedto calculate an energy balance. The gamma radiation inside the C₆₀molecule (having a frequency of approximately 10²² Hz with its speed ofradiation very close to or the same as speed of light) will be absorbedcompletely into a delocalized electron cloud (frequency equals zero) andwill increase the speed of rotation at the C₆₀ molecule. The solutioncan be found according to the equation: ##EQU5## The variable ω_(C60)represents the speed of rotation for C₆₀. For pure C₆₀, this rotationrate starts either at or below a threshold value of 2.9972×10¹⁰ s⁻¹,depending on the material state. (This rate is referred to elsewhere inthis document as approximately 3×10¹⁰ s⁻¹) The C₆₀ f.c.c. solid staterotation rate is equal to the threshold value, 3×10¹⁰ s⁻¹ ; liquids andgasses rotate at rates less than this value. For C₆₀ with includedradioactive material (X_(rad) @C₆₀), the ω_(C60) value increases as aresult of the energetic influence of the gamma radiation. Very quickly,the rotation rate rises past this threshold value, thus sealing theinternally-generated gamma radiation from the outside world.

Turning to X-ray and neutron radiations, both X-rays and neutrons occurfar less often than alpha, beta, and gamma radiation during the storageof radioactive materials in Fullerenes. However, for completeness and todemonstrate the range of relativistic absorption, information describingC₆₀ containment of these two forms of radiation is provided.

X-rays come about when the orbital electrons in an atom are disruptedfrom their normal configuration by some excitation process, which drivesthat atom into an exited state for a short period of time. There is anatural tendency for the excited electrons to rearrange themselves andreturn the atom to its lowest energy or ground state within a time that,in a solid material, is typically a nanosecond or less. The energyliberated in such a transition from the excited to the ground statetakes the form of an X-ray photon whose energy is equal to the energydifference between the initial and final states. Like beta radiation,internally-generated X-rays from an X_(rad) @C₆₀ complex will be trappedand contribute energy to a delocalized electron cloud surrounding theC₆₀.

A pure source of X-rays will radiate energy from 5.6 to 6.2 KeV. Theelectronic structure of molecular C₆₀ will absorb only 320eV from anytype of pure source of radiation originating inside of the C₆₀(approximately 5% of X-ray energy). This means that, when absorbing pureX-ray radiation, 95% of the X-ray energy will be contained via theresonant relativistic absorption and result in both a delocalizedelectron cloud and an increased speed of rotation of the X_(rad) @C₆₀complex. If other additional forms of radiation are simultaneouslyemitted from the encapsulated material, as, for example, during internalconversion nuclear processes which yield both gamma and X-ray radiation,then greater than 95% of X-ray energy will be absorbed into thedelocalized electron cloud and the increased rotation of the C₆₀.

Another type of X-ray radiation consists of heavy charged particles.These particles behave like alpha particles and are absorbed much thesame as alpha radiation. They end up as "false helium" trapped on theinside of the cages.

The neutron is the least common type of radiation which can occur in aFullerene molecule. Although uncommon in this storage context, the issueis addressed here for completeness.

It is well known that nuclei created with excitation energy greater thanthe neutron binding energy can decay by neutron emission. Radioisotopeneutron sources located in a Fullerene molecule are based on eitherspontaneous fission or on nuclear reactions for which the incidentparticle is the product of a conventional decay process. Many of thetransuranic heavy nuclides have an appreciable spontaneous fission decayprobability.

Each fission event produces a few fast neutrons. When deliberately usedas a neutron source, the isotope is encapsulated in a sufficiently thickcontainer so that only the fast neutrons and gamma rays emerge from thesource. The energy spectrum of neutrons is from 0.2 to 5 MeV, with thepeak of the spectrum being between 0.5 and 1.5 MeV. Free neutrons havehalf lives of approximately 12 minutes, after which they each separateinto a proton and an electron. When interacting with Fullerenes, theenergy of the electron produced by neutron decay will fill one or moreof its unoccupied molecular orbitals (LUMO), while the proton willinteract through one or more occupied orbital(s)(HOMO). Energetically(similar to X-rays), a small fraction of the neutron energy (in thiscase less than 1%) will be absorbed by the electronic structure of C₆₀,but much more energy (99%) will be absorbed into the delocalized cloudand the increased rotation of C₆₀.

1.2 C₆₀ Radiation Containing Properties Depend on C₆₀ Rotation Rate

With all forms of harmful radioactive emissions, the ability of the C₆₀molecule to trap such emissions essentially depends on the Fullerene'srate of rotation. The normal rotation rate for C₆₀ is 3×10¹⁰ s⁻¹ in thesolid state. In liquids, the rate drops significantly. For example, thereduced rotation rates are 1.8×10¹⁰ s⁻¹ in Toluene and 5×10⁹ s⁻¹ inNitrobenzene. To contain emitting radiation, the X_(rad) @C₆₀ complexmust rotate at speeds greater than or equal to a threshold value, whichis equal to the C₆₀ solid state rotation rate.

If the C₆₀ rotation rate drops below approximately 3×10¹⁰ s⁻¹ then theradiation will no longer be safely contained within the storagemolecule. The slower rotation rates caused by liquid and gas states arenot a problem, however, because the encapsulation of radiation-emittingmaterials increases the rate of rotation several orders of magnitudebeyond the threshold for C₆₀ molecules in any form (gas, liquid, solid).This is particularly true of alpha and gamma radiation, which focus allor most of their energy into increasing the speed of rotation and lessinto forming delocalized electron clouds (beta and X-rays).

In order to obtain the beneficial result of containing radiation, theenvironment external to the C₆₀ storage molecule must be maintainedabove minimum temperatures and below maximum pressures. Only bymaintaining the external environment in which the X_(rad) @C₆₀ complexesare stored within a range of acceptable conditions will the X_(rad) @C₆₀complexes be able to maintain their extraordinarily high rates ofrotation (above the threshold rate) and, thereby, mitigate the radiationhazards. If the X_(rad) @C₆₀ complexes are subject to externalconditions such as those that exist in ocean waters at depths greaterthan 800 meters, then the X_(rad) @C₆₀ complexes will slow below theradiation release threshold (approximately 3×10¹⁰ s⁻¹) and the containedradiation will be released to the environment. Thus, deep ocean disposalof radioactive wastes in C₆₀ is not desirable when compared to otherless stressing geologic disposal. However, easy to achieve, land-basedstorage conditions will permit the C₆₀ storage molecule to rotate atspeeds above the radiation release threshold level and will serve tomaintain the useful radiation containment function.

2.0 Fullerene Onions

Fullerene Onions are concentric carbon cages formed in layers about acentral point. Fullerene onions can be used selectively to improve uponthe C₆₀ 's ability to contain radiation. For our purposes, Fullereneonions exist in two main classes; those with C₆₀ inside and thosewithout C₆₀ as one of the inner layers. Fullerene onions containing C₆₀can be further subdivided into two types, namely, those exhibitingperfect icosahedral symmetry and those not exhibiting such perfectsymmetry.

The following Fullerene onions or hyperfullerenes exhibit perfecticosahedral (Ih) symmetry:

    ______________________________________                                        Hyperfullerene     Inter-layer Spacing                                        ______________________________________                                        C.sub.60 @C.sub.180                                                                              0.274 nm                                                   C.sub.60 @C.sub.240                                                                              0.352 nm                                                   C.sub.60 @C.sub.540                                                                              0.701 nm                                                   C.sub.60 @C.sub.240 @C.sub.540                                                                   0.352-0.350 nm                                             ______________________________________                                    

These are significant for the containment of radioactive emissionsbecause the perfect icosahedral symmetry of their outer layers meansthere will be no resistance to the critical spinning motion of the innerC₆₀ molecule. Hence, when doped with radioactive materials, they willpossess all of the radiation-trapping Doppler effect-based resonantrelativistic absorption properties of pure X_(rad) @C₆₀.

Shells within a hyperfullerene are mobile via rotation. Indeed, the C₆₀in the C₆₀ @C₂₄₀ complex will rotate about the C₅ axis while remainingconcentrically centered. As larger shells are added to these complexes,the inter-layer energy barrier decreases. Because the pentagons remainenergetically aligned, energy differences in C₆₀ @C₂₄₀ @C₅₄₀ cause theC₂₄₀ to be compressed and become less round, while the C₅₄₀ expands andbecomes more round. In this complex, the energy of the C₆₀ pentagonsdrives the rotation of all the shells. However, the center C₂₄₀ shellspins much slower due to the energy of the C₅₄₀ pentagons, which hindersthe rotation of the second layer.

Calculations on the mobilities of the inner shell of a hyperfullerene(e.g., C₆₀ @C₂₄₀ @C₅₄₀) indicate that: 1) because of its perfectspherical shape, only the core C₆₀ cage can undergo absolutely centeredconcentric rotation in Fullerene onions and rotate at or beyond itsnatural solid state velocity of approximately 3×10¹⁰ s⁻¹ ; 2) because oftheir polygonal shape, the rotation for larger carbon shells is stronglyhindered, and 3) the C₆₀ translates along the C₅ axis freely within adistance of about 0.04 nm about its equilibrium position. Notsurprisingly, the perfect Ih symmetry three-layer Fullerene onionradioactive material complex, X_(rad) @C₆₀ @C₂₄₀ @C₅₄₀, is a veryappealing candidate as a Fullerene complex for long-term radioactivewaste disposal. The inner C₆₀ will contain the radiation viaDoppler-based effects (discussed above) and the outer layers, whichperfectly align with the pentagonal axes, will serve to reinforce theinner C₆₀, which can, after many thousands of years, build up internalforces adequate to fracture X_(rad) @C₆₀ depending on the material beingstored.

This fracturing is probable in a single layer X_(rad) @C₆₀ because theongoing radioactive decay processes that occur within the C₆₀ storagemolecule eventually can disrupt the physical integrity of the storagemolecule itself. For ²³⁹ U@C₆₀ and ²⁴³ PU@C₆₀ (two radioactive isotopesspecifically chosen because they evolve a large number of alpha andgamma particles), given the Carbon-Carbon (C-C) bond strengths availableduring high speed rotation, it will take approximately 72,000 years tobuild up sufficient internal particles and accompanying forces to causethe C₆₀ storage molecule to rupture (C₆₀ →C₅₈ +C₂). At that moment, theC₆₀ will quickly release a significant portion of the radiation trappedduring the previous 72,000 years and then forever after cease to containemitting radiation. For ²³⁷ U@C₆₀, the internal pressure builds upslower, taking approximately 10⁵ years to fracture the C₆₀ cage.Different isotopes will last varying times along these (exponential)lines. Some may never fracture their C₆₀ cages.

Even given this remarkably long duration, the eventual breakdown ofthese molecules is extremely undesirable. A safer alternative is to usea Fullerene onion to store the radioactive material. Fullerene onionsprovide the C₆₀ storage molecule with additional external restraint soas to enable that storage molecule to continue containing radioactiveemissions beyond the expected point of rupture. In particular, forreasons of both survival through a wider range of external environmentalconditions and increased duration through time, X_(rad) @C₆₀ @C₂₄₀ @C₅₄₀ideally contains harmful high energy ionizing radiation and is wellsuited for use as a long-term storage mechanism. Given its internalstrengths, this specific Fullerene onion will significantly increase thesafe depth of ocean disposal so as to make even that disposal optionfeasible.

In the case of Fullerene onions which do not exhibit perfect Ihsymmetry, the rotation rate of the inner C₆₀ may be slowed, and/or therotation of the outer layers may be drastically increased. Further, thereinforcing properties of non-symmetrical onions are decreased, makingthem less desirable for permanent storage. However, such non-symmetricalonions which include a C₆₀ storage molecule as an inner layer may beadequate for low-level waste storage or specific high-level wastes withsmaller numbers of resulting decay particulates.

Finally, even in the case of radioactive materials encapsulated withinFullerene onions that do not contain C₆₀, the emission ofinternally-generated radiation can be decreased by adding carbon layers,which act to directly absorb the radiation. While C₆₀ will contain orabsorb all internally-generated radiation via the resonant relativisticabsorption phenomena based on the Doppler effect, non-C₆₀ Fullereneonions having three overlapping carbon shell layers will partiallyabsorb such radiation based on an energetic or electronic closing of theFullerene hexagons (weak phenomenon) as well as classical absorption(weakest phenomenon).

With three or more carbon layers, each layer will overlap the others andenergetically close the hexagons and seal the energy holes found insingle layer carbon hexagonal arrays. But without the needed C₆₀rotation, these Fullerene onions will not necessarily trap allradiation. Certainly, energetic closure of the storage molecule'shexagons will decrease the intensity of escaping radiation, but suchclosure will not necessarily completely eliminate it. This energeticclosure of overlapping hexagons combined with multi-layering ofFullerene onions allows for the deliberate decrease of radiationescaping from the Fullerene/nuclear material storage cell.

This energetic closure and multi-layering also allows for the creationof tuned (amplitude via layering and hexagonal closure as well asfrequency via the selection of the included source) radiation sources.By selecting the radiation type inserted within the Fullerene and thenumber of carbon layers employed, the combination can be used to providea tuned radiation source.

3.0 Fullerene Nanotubes and Capsules

Nano-scale carbon tubules have been the subject of intensiveapplications research since their discovery in 1991. Here, we use thesemolecules to decrease the radiation released to the surroundingenvironment. For our radiation absorbing purposes, Fullerene nanotubesand capsules behave much like Fullerene onions which do not contain C₆₀or rotate at very high speeds.

The tube structures are composed of coaxial arrays of closed graphiticsheets. In any given tube, the carbon pentagons are arranged in ahelical fashion about the axis with tube-to-tube variation in the pitchangle to allow optimization of the inter-layer spacing (0.34-0.35 nm).This is slightly more than the spacing of ideal graphite and really morecharacteristic of turbostratic carbon. Because nanotubes and capsules donot rotate, they will not provide the Doppler-based resonantrelativistic absorption phenomena exhibited by the C₆₀ storage molecule.However, due to the energetic closure of the hexagons by three or morecarbon layers, nanotubes and capsules will decrease the radiation, butthey will not necessarily stop it completely.

If we bear in mind the energetic closure of layered (three or morelayers) Fullerene nanotubes and we keep in mind that some classes ofnanotubules possess metallic properties, while others possesssemiconducting properties, and yet others possess transitionalproperties between metallic and semiconducting states; then thecombination of all these properties endows these nanotubes with theinteresting potential of functioning as a radiation guide which servesto guide the emitted radiation along the primary axis of the tube orcapsule. Thus, these materials can be used to direct the radioactiveenergy emitted towards a specific location or target.

4.0 Manufacturing U@C_(n) Complexes

Experimental evidence exists for U@C_(n) complexes formed in electricarcs. It is interesting to note that during such formation, U@C₂₈ andU@C₆₀ are the most abundantly produced clusters. Keeping in mind thespecial closed-shell electronic molecular structure of C₆₀, theabundance of U@C₆₀ is anticipated. Also given the fact that the processof crystallization of C₆₀ occurs around a point, it is reasonable toexpect that one uranium atom (U@C₆₀) will be enclosed more frequentlyinside of a cage than two atoms (U₂ @C₆₀).

However, due to the common open-shell electronic structure of C₂₈, theabundance of U@C₂₈ is less easily explained. The ground electronic stateof C₂₈ (symmetry T_(d)) is ⁵ A₂, with one electron in an a₁ orbital andthree electrons in a t₂ orbital. This situation leaves dangling bondslocated at each of the four carbon atoms at the tetrahedral vertices ofthe T_(d) structure. The open-shell electronic structure of the ⁵ A₂ground state of C₂₈ is closed by the uranium atom (inside the cage) as atetravalent atom, thereby explaining the result.

Extending these observations with simple volumetric calculations, wederive a further useful conclusion. The diameter of the ground state ofC₆₀ is 0.71 nm; the C-C bond between C₆₀ and C₂₈ is 0.145 nm; and thelongest diameter of ground state of C₂₈ is 0.41 nm. Thus, it is possiblethat (U@C₂₈)@C₆₀ complexes can also be induced to form. The usefulnessof this fact for radioactive material storage techniques is clear: Sincesuch tetravalent atoms are naturally preferred in the formation phaseand still can be encapsulated within C₆₀, then waste encapsulationproduction processes can be made more efficient.

While the invention has been described in connection with what ispresently considered to be the most practical and preferred embodiment,it is to be understood that the invention is not to be limited to thedisclosed embodiment, but on the contrary, is intended to cover variousmodifications and equivalent arrangements included within the spirit andscope of the appended claims.

What is claimed is:
 1. A radiation absorbing storage molecule comprising:a Buckminsterfullerene C₆₀ molecule; and a radioactive material encapsulated within the Buckminsterfullerene C₆₀ molecule; wherein the C₆₀ molecule has an electronically closed shell and is controlled to rotate at a minimum speed of 3×10¹⁰ s⁻¹ to trap harmful radiation emitted by the encapsulated radioactive material.
 2. A radiation absorbing storage molecule comprising:a Fullerene onion having a Buckminsterfullerene C₆₀ molecule as an inner carbon cluster layer; and a radioactive material encapsulated within the Buckminsterfullerene C₆₀ molecules; wherein the C₆₀ molecule has an electronically closed shell and rotates at a speed sufficient to trap harmful radiation emitted by the encapsuled radioactive material.
 3. A radiation-absorbing molecule as claimed in claim 2, wherein the Fullerene onion has a perfect icosahedral symmetry.
 4. A radiation-absorbing storage molecule as claimed in claim 2, wherein the C₆₀ molecule rotates at a minimum speed of 3×10¹⁰ s⁻¹.
 5. A radiation-absorbing storage molecule as claimed in claim 2, wherein an outer shell of the Fullerene onion is a C₁₈₀ molecule.
 6. A radiation-absorbing storage molecule as claimed in claim 2, wherein an outer shell of the Fullerene onion is a C₂₄₀ molecule.
 7. A radiation-absorbing storage molecule as claimed in claim 2, wherein an outer shell of the Fullerene onion is a C₅₄₀ molecule.
 8. A radiation-absorbing molecule as claimed in claim 2, wherein an intermediate shell of the Fullerene onion is a C₂₄₀ molecule and an outer shell of the Fullerene onion is a C₅₄₀ molecule.
 9. A high energy, ionizing radiation decreasing molecule comprising:an energetically closed storage cell having at least three carbon layers, said three carbon layers being an inner layer, an intermediate layer and an outer layer; and a radioactive material encapsulated within the inner carbon layer.
 10. A molecule as claimed in claim 9 wherein, the carbon layers are formed by spherical Fullerene onion layers.
 11. A molecule as claimed in claim 9, wherein the carbon layers are formed by Fullerene capsules having two closed ends.
 12. A high energy, ionizing radiation directing and absorbing molecule comprising:an energetically closed storage cell having at least three carbon layers, said three carbon layers being an inner layer, an intermediate layer and an outer layer; and a radioactive material encapsulated within the inner carbon layer; wherein each of said three carbon layers is formed by a Fullerene nanotube having one closed end.
 13. A method of creating an energetically closed Fullerene structure comprising the steps of:forming a first carbon layer using a Fullerene molecule having a first configuration, encapsulating a radioactive material within the first carbon layer; forming a second carbon layer around the first carbon layer using a Fullerene molecule having a configuration which is the same as the first configuration; and forming a third carbon layer around the second carbon layer using a Fullerene molecule having a configuration which is the same as the first configuration.
 14. A method as claimed in claim 13, wherein the first, second, and third carbon layers are formed using Fullerene onions.
 15. A method as claimed in claim 13, wherein the first, second, and third carbon layers are formed using Fullerene nanotubes.
 16. A method as claimed in claim 13, wherein the first, second, and third carbon layers are formed using Fullerene capsules.
 17. A method as claimed in claim 13, wherein the first carbon layer is formed using a Fullerene capsule, and the second and third carbon layers are formed using Fullerene nanotubes.
 18. A method of absorbing radiation comprising the steps of:selecting a Buckminsterfullerene C₆₀ molecule as a storage molecule; encapsulating a radioactive material within the C₆₀ storage molecule; and controlling environmental conditions surrounding the storage molecule such that the C₆₀ storage molecule rotates at a minimum speed of 3×10¹⁰ s⁻¹.
 19. A method of optimizing the production of C₆₀ Fullerene molecules encapsulating radioactive materials comprising the step of using a tetravalent Fullerene to initiate the formation of C₆₀ shells.
 20. A method as claimed in claim 19, wherein the tetravalent Fullerene is U@C₂₈. 